Currently, low-flow fluid systems are utilized for controlled irrigation of crops, vegetation, landscaping, and the like. Commonly, these flow systems utilize a fluid or water source, a pumping system in communication with the water source, a network of fluid delivery conduits or pipes, a plurality of end point emitters for fluid dispersement, one or more control valves for opening or closing the fluid delivery conduits to turn on or off the emitters, and a number of controllers for actuating the valves. The emitters provide a slow drip or trickle flow. Furthermore, each valve may be paired with a debris trap for collecting particulate matter that cannot escape through the emitter itself. A representative low-flow system may include 10–15 valves on a single controller, and each valve may communicate with 20–100 emitters.
These low fluid flow systems are often used where water is a more scarce commodity, such as in arid and low precipitation environments where water is quickly evaporated. By using these systems, water can be delivered to landscaping in a controlled manner without spraying the water in the air where a substantial portion may evaporate quickly and without distributing the water over a surface area that will not benefit. Instead, the drip or trickle generally goes straight to the ground where it is absorbed and feeds any plants in close proximity to the sprinkle, allowing for less water waste.
By their nature, much of the vegetation that survives in an arid environment does so precisely because of low water consumption needs. Still, the attractiveness of the vegetation, such as landscaping, or the quality of crops grown, depends on a reliable delivery of water.
However, plants that have low water consumption needs typically do not respond well to over-watering. If the plants become soaked for long periods of time, the plants can die or their roots may suffer damage, such as root-rot. Furthermore, such plants often survive in loose soil or soil with a significant amount of sand, which contributes to the soil's inability to absorb excess water. This type of soil can become over-saturated easily, and the plants may not be able to remain in the loosened soil. For at least these reasons, unreliable controls and the valves for these irrigation systems can be expensive to crops.
A well-known design for low-flow valves is a diaphragm valve. This type of valve has an inlet and an outlet with the diaphragm positioned between them. A control is used to move a portion of the flexible diaphragm between a closed position that seals a passage between the inlet and outlet and an open position whereby water is permitted to flow by the diaphragm. The moving portion of the diaphragm usually includes a dome-shaped structure disposed in a facing relationship with an annular or cylindrical port intermediate the inlet and outlet. In operation, the dome presses against and into the cylindrical port to close the valve, as well as moves away from the cylindrical port to permit water to pass between the dome and cylindrical port and through the valve.
At times, foreign particulate matter, such as dirt, may be in the water passing through the conduit and the low-flow valve. Most foreign particulate matter that enters the irrigation system does not present a significant issue. In addition, most particulate matter such as dirt is relatively small. When dirt moves with the water stream through the system, most of such dirt will pass through the valve without issue. However, some dirt can become lodged between the cylindrical port and the dome when the dome attempts to move from the open position to the close, thereby trapping the dirt between the cylindrical port and the dome.
At times, the particulate matter may be introduced during the construction or operation of the low-flow system itself. For instance, the fluid delivery pipes are often polyvinyl chloride (PVC) piping that is custom fit at the connections. When cutting or otherwise preparing the PVC piping, it is recognized that some shavings or waste material may enter the pipe itself, eventually being passed through the system to the low-flow valve. PVC shavings and other material that is neutral buoyant, or materials that do not sink in stagnant water, will follow the water stream without a significant flow rate. Accordingly, these materials may have a much larger size than the previously discussed dirt particles. This size frequently can be larger than the gap between the dome and the cylindrical port of the opened low-flow valve, and can become lodged against or within the gap.
In the event dirt or other foreign material becomes trapped between the dome and the cylindrical port, the valve may not close sufficiently and will allow an undesirable amount of water to still pass through the valve. The material may become lodged when the valve is open and the dome is positioned away from the cylindrical port, or it may become caught when the dome moves towards and against the cylindrical port as the valve is being closed.
The trapped material can prevent the valve from properly closing. More specifically, dirt or other material lodged between the dome and the cylindrical port may allow a portion of the dome adjacent to the material not to contact the cylindrical port. In such an event, an undesirable amount of water may continue to pass through the valve. This may result in an unnecessary use of water or in over-irrigation of the soil and plants, as well as other undesirable results.
In a typical valve of this kind, closing the valve can be violent and provide shock to the flow system and valve. For instance, the dramatic drop in flow can cause rapid changes in pressure along the system. In addition, as the valve is closing, the water passing therethrough will accelerate as it tries to pass through an ever-narrowing opening. This causes a high amount of friction between the water and the dome or diaphragm, causing the diaphragm to be pulled towards the cylindrical port or diaphragm seat. More specifically, the diaphragm is rapidly accelerated into the seat, thereby causing the diaphragm to bounce against and away from the seat. When the diaphragm bounces in this manner, it moves away again from the seat and allows more water to pass through the valve. This may be repeated multiple times, and will continue until the force pushing the diaphragm into a seated, generally closed position damps and overpowers this bouncing or vibration.
Accordingly, there has been a need for an improved low-flow valve.